The goal of this project is to develop STC101, a biosmilar Herceptin. Trastuzumab is a monoclonal antibody made against the HER2 protein that is overexpressed in 20-25% of patients with breast cancer. Because of high cost associated with prescribing Herceptin, a generic version of this drug would make this cancer treatment more affordable to a wider segment of the population and lower the cost burden on government-sponsored healthcare programs. STC Biologics Inc. is uniquely positioned to address the technical challenge of reverse engineering trastuzumab as its drug development platform offers rapid and efficient analysis of post-translational modifications of recombinant proteins.During the phase I contract, STC Biologics Inc. provided a proof of concept studies showing the feasibility of making a biosimilar trastuzumab, STC101 that is analytically similar to the branded equivalent. . We have thoroughly analyzed three lots of Herceptin for post-translational modifications, to quantify the observed range of variation; this information has served as a guide for STC101 process optimization. During Phase II of the SBIR contract, we plan to complete STC101 preclinical development. We propose to develop a scalable and reproducible process to produce STC101. STC will examine the activity of STC101 and compare to to Herceptin in various assays required for the regulatory approval in the U.S. and abroad.